Sash balance



D. TAPPAN SASH BALANCE Filed Aug. l, 1959 g/ "ZA FIG |v May 13, 1941.

Patented May-i3, i941 un". 'tras sasn BALANCE Applicatien August l, 1939, Serial No. 287,771

`(C1. lf3-198) Claims.

This invention relates to sash balances of the type in which an involute spring is used to counterbalance the weight of the ash so as to facilitate an easy movement thereof.

Sash balances of this type cannot perfectly balance a freely fitted window sash in all yof its positions because the involute spring will exert a gradually increasing or decreasing pull as it is being wound up on the down movement of the sash or unvvound on the up movement thereof. For this reason a sash suspended by such a balance has a tendency to drop back from its uppermost position because the partially unwound spring will exert at that point a pull of reduced strength in its action to balance the sash. On the other hand the sash will have a tendency to "rise from its lowermost position because the wound up spring will at that point exert an increased pull in its action to balance the sash. To overcome this difference in the pull of the spring it is common practice to frictionally engage the window sash so that it will move substantially uniformly whether a reduced or increased pull is exerted by thespring during the movement of the sash, or to provide the sash balance with friction means for this purpose or use both of these means to suciently compensate for the varying pull of the spring in order to secure a balance for the sash. The rst mentioned practice is only practical as long as the window sash remains properly fitted in its run, whereas the use of friction means in the sash balance is only practical if the friction means are properly adjustable and in such a manner that the adjustment may be readily made at any time after the installation of the sash balance.

The principal object of my invention is therefore to provide a sash balance with variable friction means which can be adjusted at will so as to substantially uniformly balance the sash in any of its positions.

A further object of the invention is to so embody the friction means in the sash balance so that it may be readily accessible for adjustment at any time.

Another object of the invention is to provide the sash balance with a novel mounting member for its spring.

Still another object of the invention is to provide novel attaching means for the metal ribbon with which the balance is connected with the sash. Y

All these and other objects of this invention will become morev readily apparent from the detailed description thereof which follows, reference being had to the accompanying drawing in Which- Figure 1 is a front elevation of my improved sash balance with its cover removed from it as it I appears mounted in the head jamb of a window frame.

Figure 2 is an end elevation of the sash balance.

Figure 3 is a vertical sectional View of the sash balance taken on the line 3,3 of Figure 2.

Figure 4 is a cross section of the sash balance, the section being 'taken on the line 4,4 of Figure 1.

Figure 5 is a detail perspective View of the adjustable friction member of the sash balance.

Figure 6 is a detail perspective View of a portion of the drum of the sash balance at the point where the connecting ribbon is anchored thereto.

Figure 7 is a detail perspective View of the end of the connecting ribbon as it appears prepared for attachment to the drum of the sash balance.

As illustrated in the several figures of the drawing the spring sash balance forming the subject matter of my present invention comprises a face plate I on which is mounted the base 2 of the supporting wall 3. Suitable braces 4 and 5, one at each end of the base 2 rigidly hold the supporting Wall in its vertical position on the base. Mountedon the supporting wall is the post 6 which is surrounded by a circular disc forming a base flange l. Integrally formed lugs or rivets 8,8 'carried by the flange l project thru corresponding perforations in the supporting Wall 3 and are headed over on the outside so as to firmly hold the ange l and with it the posts 6 on the supporting Wall.

The outer portion of the circular fiange is reduced in thickness and thus spaced from the supporting wall to form a circular channel 9 therebetween. Mounted for rotation in this circular channel is the back of the drum I0 which, for this purpose, is provided with a central opening surrounded by the circular offset ange II. The latter is held in place in the circular channel 9 s0 as to freely rotate therein and hold the drum pivotally mounted on the supporting wall.

The drum I0 houses the involute spring I2 which has its inner end anchored to the post 6 thereof which, for this purpose, is hollow and has a slot I3 thru which the end of the spring is hooked for anchorage thereto. In order to keep the inwardly projecting end of the Spring from extending over the hollow center of the post, a lug M is formed on one side of the slot i3 and angularly projects into the vhollow post so as to deflect the end of the spring to one side of the center for a purpose that will presently appear. As illustrated in dotted lines in Figure 4, the outer end of the lug I4 is-inclined longitudinally adjacent the outer end of the opening in the post. The outer end of the involute spring is hooked over the flange I5 which is offset inwardly from the outer wall ofthe drum.

The metal ribbon I6 with which the sash is connected with the sash balance, is wound on the outside of the drum I and is attached to the triangularly shaped inwardly bent lug I'I located in the opening I8 in the wall of the drum as illustrated in Figure 6. To provide for a quick and firm attachment of the metal ribbon to this lug, the end of the ribbon is transversely folded finger, a limited movement of each linger relative to the other is also possible.

As above pointed out the heads of the bolts are located in the face plate I of the sash balance which is exposed in the runway of the sash so that the adjustment of the friction member can be easily and quickly made at any time by means of a suitable screw driver.

The drum is covered by a hood 21 which spacedly encircles the outside of the drum Il) Y from one side of the base 2 to the other side over the bottom of the ribbon and then over the top thereof. In making the transverse fold over the bottom of the ribbon, the folded edge extends at an angle across the ribbon while the fold over the top of the ribbon provides a folded edge along one side and adjacent the end ofv the angularly folded edge so that these two folded edges form a triangular pocket I9 at the end of the ribbon. This pocket is adapted to be telescoped over the triangular lug II within the opening I8 so that the entire end of the ribbon is located within the drum as illustrated in Figure 1 and is held wedged between the lug and the wall of the drum. r

The offset flange II spaces the drum It from the supporting wall 3 and provides room for the friction member to operate therebetween. This friction member comprises a pair of tapered fingers 2l and 22 which are spacedly connected near their bottom by the cross member 23. From the bottom of each finger angularly project a flange ZIA and 22A respectively and a rib 24 extends from each of these flanges to its nger to permanently hold each flange in its angular position relative to its finger.

Each flange 2 IA and 22A has a hole 25 therethru and thru these holes `and corresponding holes in the base 2 and base plate I extend a pair of bolts 26 which have the nuts 21 threaded thereon above the flanges ZIA and 22A.v The heads of the bolts are rotatable with a screw driver on the outside of the base plate I so as to thread the nuts back and forth on the bolts and draw them against the flanges 25A and 22A or have them move away therefrom. One side of each nut normally rests' against the friction fingers so as to keep the nuts from rotating when the bolts are rotated in the adjustment of the friction member.

The ngers 2I and 22 are tapered toward their outer ends so that when forced against the back of the drum their frictional contact' therewith is gradually increased toprovide for a variable braking power in the adjustment thereof. Forcing the fingers against the drum by means of the bolts 26 therefore not only increases the pressure against the drum but as the fingers are flexed in their adjustment the resulting frictional resistance increases with the increased contact of the gradually widening contacting area of the fingers. In this way the frictional resistance provided by the ngers to thev rotation of the drum may bel adjusted so as to properly balance the weight of the sash in any of its positions against the transmitted tension of the spring. Furthermore by dividing the friction member into two contacting fingers and locating the adjustmentl thereof at the bottom of Yeach thereof. It also covers the open side of the drum and is flxedly held in place by the bolt 28 which passes thru a central opening in the hood into the hollow post 6 and is threaded into the base of the post. The lug I4 and its longitudinally inclined outer end, above described, serves to deflect the inwardly projecting end of the spring on its insertion into the opening of the post. In this way the inner end of the spring cannot interfere with the bolt 28 in its passage thru the hollow post and thus facilitates a quick and easy fastening of the cover over the drum.

1. A spring sash balance comprising an elongated base, a supporting wall held erect on said base longitudinally thereof, a post on said wall, a drum mounted to rotate around said post spaced from said supporting wall, a friction member mounted to rock on said base and projecting between said drum and supporting wall, a flange at the bottom of said friction member extending transversely over said base, an adjusting member passing thru said base for movement of said friction member into yielding frictional contact with said drum, an involute spring lmounted within said drum for movement thereof,

anda flexible tape anchored to and wound on said drum for connection with `a sash.

2. A spring balance comprising a base, a sup- I' ing contact with said drum, a spring carried within said drum for rotation of said drum and a flexible tape anchored to and wound on said drum for connection with a sash.

3. A spring balance as set'forth in claim 2 in which said friction memberi has a flange extending angularly from the bottom thereof to provide a rocking edge for said friction member for its support on said base, and bolt means engaging said flange and operated by said adjust.. ing means for movement of said friction member.

4. `A spring balance as set forth in claim 2 in which said friction member is bifurcated to pro- Y vide a pair of friction fingers for individual engagement of the drum on each-side of the pivotal mounting thereof, and in which said friction member is provided with a plurality of adjusting means adapted to collectively and separately vary the yielding contact of the fingers with said post, an elongated lug carried by and eX- tending longitudinally within said post and angularly projecting over the opening thereof, a longitudinally inclined end provided on said lug substantially adjacent the outer end of the opening in the post, an involute spring anchored to the post on the insertion of the spring into said drum with the inner end of the spring engaging into the opening in the post and deflected to one side of the hollow center over one edge of l0 the opening in the post by the longitudinally inclined end of said lug and the angular projection of the lug over the opening in the post, a. connecting tape carried by said drum, a cover extending over said drum for support on said supporting Wall, and clamping means extending thru said cover and said hollow post for clamping said cover to said supporting Wall.

DEWITT TAPPAN. 

